Touch panels are currently newest information input devices, and can simply, conveniently and naturally implement human-machine interaction and provide a brand new multimedia human-machine interaction method, making people feel visual and tactile enjoyment. With rapid changes of display technology and increasingly fierce competition, it has become a trend to implement a touch display structure with a low cost and high performance.
Display devices with a touch control function can be divided into a resistance type, a capacitance type, a surface acoustic wave type, an infrared type and the like according to the sensing principle, and can be divided into an out-cell structure, an on-cell structure and an in-cell structure according to the structural relation between a touch panel and a display screen.
At present, most touch panels adopt an out-cell structure, and in an out-cell technology, generally a touch panel and a display (such as liquid crystal display, abbreviated as LCD) screen are manufactured separately and then fit together. Such a structure has shortcomings of a complex process, a high cost, a low transmittance, a thick module and the like.
As to an in-cell structure, since a touch structure is embedded in a display screen to achieve touch and display integration, lightness and thinness of a display device are readily achievable and the production cost can also be reduced, and thus touch display devices with the in-cell structure are very popular for manufactures in the display field. However, in the existing in-cell technology, generally both a sensing electrode and an emitting electrode for achieving the touch control function are arranged in an array substrate, so a complex semiconductor manufacturing process must be used to form the array substrate, which results in a low production yield of the array substrate; furthermore, embedding a touch sensor (such as sensing electrode and emitting electrode) in a pixel structure of the display screen can reduce an effective area available for display, leading to degradation of display effect.
Thus, it has become one of important issues for designers currently to design a touch display panel with a high transmittance, a simple structure, a simple manufacturing process and a low cost.